@Comic_Sans_MSIt already been addressed and corrected by " Quadriplegic" about how the 80+ Efficiency rating actually works so i now know.
And I don't understand why you have you are so salty about my crappy old PSU that I'm trying to get rid of? The box for the RX Vega 64 Recommends a 1000W PSU, well over what my current one is and slightly over what I've been looking into.
The CoolerMaster CM Storm 550W 80+ Bronze is not a bad PSU and has a decent rating in Australia. It's got C6 and C7 support for my CPU and has worked perfectly for a few years now, only having issues when my GPU is in Turbo or a custom OC setting. Yes, it is a Tier D PSU but that's fine for my old budget build with a RX480. I think you are the that has no idea what they are talking about. 550W IS NOT ENOUGH, every single PSU calculator estimates that it should draw over 600W. Right now, under minimal load on a 900mv Undervolt, i'm drawing close to the limit of my current PSU.